Add iLBC codec

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@852 65c4cc65-6c06-0410-ace0-fbb531ad65f3

codecs/ilbc/LPCdecode.c

@@ -0,0 +1,121 @@
+ 
+/****************************************************************** 
+ 
+    iLBC Speech Coder ANSI-C Source Code 
+ 
+    LPC_decode.c  
+ 
+    Copyright (c) 2001, 
+    Global IP Sound AB. 
+    All rights reserved. 
+ 
+******************************************************************/ 
+ 
+#include <math.h> 
+#include <string.h> 
+ 
+#include "helpfun.h" 
+#include "lsf.h" 
+#include "iLBC_define.h" 
+#include "constants.h" 
+ 
+/*----------------------------------------------------------------* 
+ *  interpolation of lsf coefficients for the decoder                            
+ *---------------------------------------------------------------*/ 
+ 
+void LSFinterpolate2a_dec(  
+    float *a,           /* (o) lpc coefficients for a sub frame */ 
+    float *lsf1,    /* (i) first lsf coefficient vector */ 
+    float *lsf2,    /* (i) second lsf coefficient vector */ 
+    float coef,         /* (i) interpolation weight */ 
+    int length          /* (i) length of lsf vectors */ 
+){ 
+    float  lsftmp[LPC_FILTERORDER]; 
+     
+    interpolate(lsftmp, lsf1, lsf2, coef, length); 
+    lsf2a(a, lsftmp); 
+} 
+ 
+/*----------------------------------------------------------------* 
+ *  obtain dequantized lsf coefficients from quantization index  
+ *---------------------------------------------------------------*/ 
+ 
+void SimplelsfDEQ( 
+    float *lsfdeq,      /* (o) dequantized lsf coefficients */ 
+    int *index          /* (i) quantization index */ 
+){   
+    int    i,j, pos, cb_pos; 
+ 
+    /* decode first LSF */ 
+     
+    pos = 0; 
+    cb_pos = 0; 
+    for (i = 0; i < LSF_NSPLIT; i++) { 
+        for (j = 0; j < dim_lsfCbTbl[i]; j++) { 
+            lsfdeq[pos + j] = lsfCbTbl[cb_pos +  
+                (long)(index[i])*dim_lsfCbTbl[i] + j]; 
+        }        
+        pos += dim_lsfCbTbl[i]; 
+        cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; 
+    } 
+ 
+    /* decode last LSF */ 
+     
+    pos = 0; 
+    cb_pos = 0; 
+    for (i = 0; i < LSF_NSPLIT; i++) { 
+        for (j = 0; j < dim_lsfCbTbl[i]; j++) { 
+            lsfdeq[LPC_FILTERORDER + pos + j] = lsfCbTbl[cb_pos +  
+                (long)(index[LSF_NSPLIT + i])*dim_lsfCbTbl[i] + j]; 
+        }        
+        pos += dim_lsfCbTbl[i]; 
+        cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i]; 
+    } 
+} 
+ 
+/*----------------------------------------------------------------* 
+ *  obtain synthesis and weighting filters form lsf coefficients  
+ *---------------------------------------------------------------*/ 
+ 
+void DecoderInterpolateLSF(  
+    float *syntdenum,   /* (o) synthesis filter coefficients */ 
+    float *weightdenum, /* (o) weighting denumerator  
+                               coefficients */ 
+    float *lsfdeq,      /* (i) dequantized lsf coefficients */ 
+    int length,         /* (i) length of lsf coefficient vector */ 
+    iLBC_Dec_Inst_t *iLBCdec_inst  
+                        /* (i) the decoder state structure */ 
+){ 
+    int    i, pos, lp_length; 
+    float  lp[LPC_FILTERORDER + 1], *lsfdeq2; 
+         
+    lsfdeq2 = lsfdeq + length; 
+    lp_length = length + 1; 
+     
+    /* subframe 1: Interpolation between old and first */ 
+ 
+    LSFinterpolate2a_dec(lp, (*iLBCdec_inst).lsfdeqold, lsfdeq,  
+        lsf_weightTbl[0], length); 
+    memcpy(syntdenum,lp,lp_length*sizeof(float)); 
+    bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length); 
+ 
+    /* subframes 2 to 6: interpolation between first and last  
+    LSF */ 
+     
+    pos = lp_length; 
+    for (i = 1; i < 6; i++) { 
+        LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2, lsf_weightTbl[i],  
+            length); 
+        memcpy(syntdenum + pos,lp,lp_length*sizeof(float)); 
+        bwexpand(weightdenum + pos, lp,  
+            LPC_CHIRP_WEIGHTDENUM, lp_length); 
+        pos += lp_length; 
+    } 
+     
+    /* update memory */ 
+ 
+    memcpy((*iLBCdec_inst).lsfdeqold, lsfdeq2, length*sizeof(float)); 
+ 
+} 
+ 
+